var HiddenPixels;
var i, stopsliding;
var intHide, intShow;
var speed=3;
stopsliding=0;

function InitializeVars(){
	HiddenPixels = document.getElementById("preview_list_div").offsetHeight - document.getElementById("slider").offsetHeight;
	i = parseInt(document.getElementById("slider").style.top);
}

function Slide(dir)
{
	stopsliding=0;
	if(dir==-1) {
		window.clearInterval(intHide)
		intShow=window.setInterval("show()",1)

	}
	if(dir==1) {
		window.clearInterval(intShow)
		intHide=window.setInterval("hide()",1)

	}
}

function StopSlide(dir){
	stopsliding=1;
	window.clearInterval(intHide);
	window.clearInterval(intShow);
}

function show()
{

	if ((i>HiddenPixels)&&(!stopsliding)){
		i=i-speed;
		document.getElementById('slider').style.top=i;
		
	}else{
		window.clearInterval(intShow);  
		intShow = null;
		stopsliding=1;
	}
}

function hide()
{
	if ((i<0)&&(!stopsliding)){
		k=k+speed;
		document.getElementById('slider').style.top=i;
	}else{
		window.clearInterval(intHide);  
		intHide = null;
		stopsliding=1;
	}
}